SACRAMENTO - Today, the California Air Resources Board adopted the nation's first regulation to prohibit indoor air cleaners from emitting more than 0.050 parts per million of ozone.

Some air cleaning devices, called ozone generators, have been shown to produce indoor ozone concentrations several times higher than the state's outdoor air quality standard. CARB's new regulation prohibits the sale of devices in California that produce enough ozone to harm human health. The standard of .050 parts per million will assure that concentrations remain below that level. Some devices exceeding these levels may be exempted but only for industrial use and where exposures are already regulated.

There are many types of air cleaners using a variety of technologies to remove pollutants from the air in homes and offices. Some produce ozone intentionally and others as a by product of the electronics. The law mandating CARB act, Assembly Bill 2276 signed into law in the autumn of 2006 targeted those consumer devices that produce large amounts of ozone.

"People with respiratory problems need to be protected from ozone," said Mary Nichols, Chairman of the Air Resources Board. "Consumers bought these devices hoping to reduce suffering for themselves or a loved one, only to make the situation worse."

An ARB-funded survey by the University of California at Berkeley, found that in the last five years 50 percent of California households that purchased air cleaners did so to address asthma and allergy problems. Forty five percent of those homes included children.

Ozone is the main ingredient of smog and is the primary target of numerous local, state, and federal health-protective measures. Very low exposure is tolerable to humans but at higher levels adverse and even dangerous health effects can result. Much research and analysis has led California to establish an outdoor ozone standard of 0.070 parts per million over an 8-hour period, and 0.090 parts per million over a one-hour period. Exposure beyond this level can lead to lung inflammation and impaired functioning, coughing, chest tightness, shortness of breath, worsening asthma symptoms, hospitalization due to respiratory issues, and potentially death. The new regulation will prevent this type of dangerous exposures to an estimated 500,000 Californians.

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Some manufacturers of ozone generators have argued that ozone has the ability to reduce levels of indoor air pollutants. Research has shown that the opposite is true. Ozone reacts with certain indoor chemicals to form ultra fine particles, which are respiratory irritants, and formaldehyde, a known human carcinogen. Manufacturers also alleged that ozone reduces odors and kills mold and bacteria in the air. However, while ozone can react with some odorous chemicals, it also irritates nasal passages and degrades one's sense of smell, thereby masking the smell rather than eliminating it. Ozone can kill microbes in the air but only at concentrations roughly 100 times greater than the amount allowable by this regulation.

Michael T. Kleinman, a professor of Environmental Medicine at the University of California at Irvine, supports the board's actions, "Ozone is associated with human deaths. It can cause irreversible changes such as fibrosis-like stiffening of the lung." Kleinman added, "In my opinion, the use of an ozone-generating device as an indoor air cleaner is dangerous, especially if occupants already have lung or heart diseases, or are elderly."

The new CARB regulation also requires all air cleaners pass an electrical safety test to prevent fire hazards. They must also carry a specified label on packaging that helps consumers identify acceptable CARB-certified air cleaners. Any air cleaning device designed for use in a single room, a whole house, an entire floor in a multi-story commercial building, inside cars, as well as "personal air purifiers" worn around an individual's neck is subject to this regulation.